As an important transmission medium of a comprehensive wiring project, the performance of optical fiber is particularly important, especially the optical fiber cable laid in the air or underground pipeline. Therefore, before the optical fiber is laid, we must test the optical fiber and the optical fiber equipment. What problems will we encounter during the testing process?
Fiber optic cable testing
1. Why use a special reference jumper to set the reference value during optical fiber testing?
The accuracy of the test results is closely related to the setting of the reference value. If the reference value is not set properly, the test result will be inaccurate or negative value will be generated. The recommended method is to use a reference light jumper and adapter when setting the reference value.
In the TIA/EIA 568-B.3 and ISO 11801 standards, the loss requirement for a fiber coupling is less than 0.75dB. The performance of fiber patch cords and adapters produced by most manufacturers can meet or exceed this requirement. However, what many people don't know is that the standard has special requirements for reference patch cords and adapters. It is stipulated in the IEC 14763-3 standard that when the reference patch cord and adapter are in use, the coupling loss of multimode fiber is less than 0.1dB, and that of single mode fiber is less than 0.2dB. Conventional fiber patch cords simply cannot meet this requirement. Therefore, it is recommended to purchase special reference jumpers from manufacturers and test equipment manufacturers for testing.
When setting the reference value, a fiber optic adapter with zirconia ceramic sleeve material is required to obtain the best coupling effect. The general practice is to use a single-mode fiber adapter to set the reference value to obtain the best coupling effect, whether testing multimode or single-mode fiber links.
2. What is the importance of preheating the tester when starting the fiber link loss test?
Generally, the higher the temperature of the light source module, the greater the power value of the light source it emits. During the test, the light source module needs to warm up for a period of time so that the transmitted light source power value can be stabilized. If the reference value is set before the light source module is preheated, as the temperature of the light source module rises, the test result will gain gain, thus affecting the accuracy of the test result.
For example, when the reference value is initially set, the power value received and stored by the optical power meter is -6.00dB. At this time, if the reference value setting model is maintained and the test is directly performed without adding the link under test, a test result of 0.00dB should be obtained. However, after the optical power module is preheated, the output power will increase, and the power value received by the power meter may rise to -6.20dB. At this time, test again, and a gain of -0.2dB will be obtained.
The preheating time of the light source module is related to the temperature of the test environment. The method to check whether the light source module is stable is very simple. As long as the reference value setting is completed, the reference value model is tested, and the obtained test value is acceptable between -0.04dB and 0.04dB; value, you need to wait for a while and reset the reference value.
3. Why does a negative value appear when testing loss? Does the link under test not only have no loss, but also gain?
When testing a single-mode fiber link, if the length of the tested link is less than 100m and the entire link is connected by pigtail fusion, the loss of the entire link may be only 0.15dB. In this case, the preheating time of the light source module is not enough, the temperature of the test environment changes greatly, the coupling effect of the reference jumper and the test instrument, and the reference value setting is not accurate enough, etc., all of which may cause the test result to get a negative value, such as -0.03dB. At this time, it is necessary to allow the machine to fully warm up and reset the reference value.
ZR Cable is a leading optical communication product manufacturing brand, focusing on R&D, production and sales of optical communication products, such as optical fiber jumpers, optical fiber terminal boxes, optical fiber splice boxes, optical fiber distribution boxes, optical fiber adapters, optical fiber demultiplexers, data center integrated wiring system, etc. ZR Cable has strong technical development, testing and production capabilities, as well as advanced quality and safety assurance systems.
